8 debt is not a "pretty high cost", honestly. It's hard to describe debt cost, but basically, it take two turns to buy a debt card unless it's really late, and you get the benefit of using the debt card in the second turn. Buy it right before you get your Trasher in the shuffle! That's productive.
City Quarter is among the most powerful draw cards in the game. More often than you would initially expect, it is basically a Madman that never leaves your deck. With just a little support - even weak trashing, Ironworks + a cantrip, Rats, Magpie... you can draw your deck with like three of these. And it's a Village too! All for only 8 debt! That's not a crippling amount.
I like it a little earlier than you think you want it, except in discard attack games. 2 cards 2 actions would be worth 8 debt, and this can sometimes do way more than that.